My grandma gave me a set of Rush Hour puzzles as a small child, ever since I could be trusted to not eat the pieces. I still enjoy playing these today and would like to try my hand at making some like it. They are a kind of sliding-blocks puzzle. The set-up is:
- 6-by-6 gameboard, completely encircled by a barrier except for 1 exit in one of the middle rows of the right edge.
- Various cars/trucks, each 2-by-1 or 3-by-1, in various orientations.
- One special red car which is always somewhere in the exit row.
- Cars/trucks can only be moved in the direction of their long axis (i.e. a truck pointing vertically can only be moved vertically).
- Each puzzle: the particular arrangement of cars/trucks to start with would be laid out on a card.
- To win: slide the cars/trucks around such that, without anything leaving the gameboard or going through each other, the red car exits off the right side.
One of my fondest memories with the puzzles was when I realized that, in order to solve the puzzle, I had to move the red car all the way backwards (i.e. leftwards), shuffle the other pieces, and only then would there be a clear route out. There have been other "ah-hah!" moments since, mostly realizations that the key to the entire thing was getting a single innocuous car to be in a certain location. Once the central secret of the puzzle was uncovered, everything became much simpler. Typically I would focus on accomplishing this new all-important sub-goal (get car X to spot Y) and once that was done everything else fell into place.
I would like to make puzzles where the difficulty is coming to the "ah-hah!" moment, which is both necessary to solve the whole thing and, once accomplished, sufficient to make the rest of the puzzle comparatively simple. How would I approach designing such a puzzle?
Difficulties I've considered
I've made grid-deduction puzzles before with (what I hope were) interesting "ah-hah!" moments. However, I feel like I had much more control there. For one thing the board was static. I could set up a clue at one end and, no matter what else I did with the solution path, that clue would be in the same place for when it was needed. With a sliding-blocks puzzle I don't have such a luxury. The blocks/cars literally slide around. The whole point is for them to be constantly in motion.
Given that, how can I make sure that there is no way for the player to get around thinking of my "ah-hah!" trick? Something I dislike is over-stuffing the board with cars. Having so many serves to distract from the important parts, which might be useful/fun, but can also make the puzzle much more of a slog. Even after all the fun solving is done these annoying small cars will still need to be shuffled around. Often there will be only one option for each move, so there is no thinking to do.
I do not want to go down that road if at all possible; at the very least I'd like to minimize the effect. The simple puzzles, with few cars but still high difficulty, always seemed much more elegant to me. Visually seeming to have less obstacles, yet still running into difficulties accomplishing what "should" be an easy task, always turned on my "there's a trick" internal alarm. Indeed, there was typically a trick!
Of course I could rely on computers to either generate or check the puzzles. The former is immediately out of the question because I enjoy making puzzles by hand, not letting a program (even one I made myself) do it for me. The latter could theoretically be used to make sure that the "ah-hah!" moment is necessary, but also feels vaguely like cheating since I like for the logic of my puzzles to be understandable to a human. The most important human being me, for double-checking purposes.
What I'm looking for in answers
A good answer should directly address the bolded question in my "Goal" section. It would lay out a strategy or some key tips to keep in mind when designing a puzzle to my liking. It would also address at least some of the difficulties brought up in the "Difficulties I've considered" section. Finally, it should be based on some experience making puzzles like this, or at least something similar enough that the experience carries over.
Frame challenge answers would also be acceptable, provided they still address the bolded question. If some premise in my question is wrong/misguided, I'd welcome someone pointing out what the problem is. The one premise that should not be questioned is the goal I'm trying to achieve. (I don't actually want to do something else; this is not an X-Y problem.) However any premise contained in my "Difficulties I've considered" dithering is fair game.